Abstract: Hawthorn fruits( Crataegus pinnatifida Bge. var. major N. E. Br.) were exposed to different dosage of shortwave ultraviolet light( UV- C) irradiation and then stored at room temperature. Effects of UV- C radiation on contents of total phenolics,flavonoids,triterpene acids,reducing sugar,titratable acid,as well as antioxidant capacity of howthorn fruit were studied. Results showed that contents of total phenolics,flavonoids,triterpene acids,and antioxidant capacity increased after illumination in 24 hours,while fruit quality were not damaged.Synthesis of phenolics and titratable acid of howthorn illuminate with UV- C was time- and dosage- depended.Compared with the control and other levels,the high dosage of UV- C made greater contribution to the enhancement of total phenolics,flavonoids,triterpene acid and antioxidant capacity.